Method of assembling medical flushing valve

ABSTRACT

A valve for an arterial monitoring set which continuously supplies a small flow of parenteral liquid, such as normal saline, into a patient&#39;s artery while arterial pressure is being continuously monitored. The valve has a flow restrictor providing a normally slow continuous flow rate and an elastically distortable tube which is manually squeezable to provide a fast flush rate. The valve is convenient for one hand operation. A method for assembling the valve by twisting the tube is also disclosed.

This application is a division, of application Ser. No. 32,832, filed4/24/79, now U.S. Pat. No. 4,267,835, issued 5/19/81.

BACKGROUND

U.S. Pat. No. 3,581,733 describes a system for continuously monitoringblood pressure within blood vessels and the heart. The system includes acatheter joined to a connecting tube leading to a pressure transducerthat converts physical pressure signals into an electrical impulse whichis then fed to a recording machine, such as an oscilloscope. As pressurereadings can be seriously affected if blood should coagulate in any partof the pressure monitoring system, this patent describes continuouslyforcing a very slow flow of a physiological salt solution (normal salinewould be an example) into the patient. This very slow flow rate issufficient to prevent blood from backing up into the catheter andconnecting tube, but is so slow that it does not cause any significanterror in blood pressure reading.

Immediately after connecting the system to the patient and periodicallythrough pressure monitoring, it becomes necessary to flush a largeramount of parenteral liquid into the patient, particularly to insurethat the catheter or needle is completely free of blood. U.S. Pat. No.3,581,733 does this flushing by a valve 18. Another type flushing valveis described in U.S. Pat. No. 3,675,891. The set up of the valve of thislatter patent is described in the attached instructions for the valvemade under Patent 3,675,891. This flushing valve has an elongated stemthat must be pulled to actuate the valve. If the valve is not physicallyanchored to a rigid IV pole, transducer, etc., this operation requirestwo hands; i.e., one to hold the valve and one to pull the stem. Shouldthe stem ever break off during the pulling action, the valve would berendered useless. In addition, the valve of U.S. Pat. No. 3,675,891includes a very large number of complicated parts including specialsealing gaskets, etc.

SUMMARY OF THE INVENTION

The present invention overcomes the problems described above andprovides a flushing valve with a restrictor in an elasticallydistortable tube. The restrictor combines with the tube to form a slowflow rate passage and the tube is distortable, such as by squeezing, totemporarily form a flush passage with a much faster flow rate. Anassembly method for the valve is described in which a pair of hollowconnectors are joined to the elastically distortable tube and moved intoabutting contact with the flow restrictor.

THE DRAWINGS

FIG. 1 is an elevational view of a blood pressure monitoring systemwhich includes the medical flushing valve;

FIG. 2 is an enlarged view of the flushing valve;

FIG. 3 is a sectional view taken along line 3--3 of FIG. 2 showing thevalve in its unsqueezed condition or its normal slow flow rate;

FIG. 4 is a view similar to FIG. 3, but showing the valve squeezed intoits temporary fast flush condition;

FIG. 5 is an enlarged view, partially in section, taken along line 5--5of FIG. 2;

FIG. 6 is an end view taken along line 6--6 of FIG. 5;

FIG. 7 is a perspective view of a hollow connector of the valve;

FIG. 8 is a sectional view taken along line 8--8 of FIG. 5;

FIG. 9 is a sectional view taken along line 9--9 of FIG. 5 showing theposition of the tube during assembly; and

FIG. 10 is a sectional view similar to FIG. 9, but showing the positionof the tube after assembly.

DETAILED DESCRIPTION

In FIG. 1, a system is shown for continuously monitoring blood pressure.This system has a hollow member 1, such as a needle or catheter,inserted into a patient's vein or artery. Usually blood pressure iscontinuously monitored from an artery because this gives a more accurateand dynamic reading of the heart function. Hydraulic pressure from thepatient's artery is transmitted through a connecting tube 2 which canhave ports or stopcocks, such as 3 and 4, for bleeding off blood samplesor injecting medication into the patient. Tube 2 connects to a rigidT-connector 5 which is shown attached to a rigid arm 6 of a transducerpressure dome 7. It is understood that the term T-connector is used inits broad sense to also include an angled Y-connector. The transducerdome 7 includes a bleed valve 8 for use in eliminating all air from thesystem prior to use. It is important that no air bubbles be in thesystem because this can affect the hydraulic liquid pressure wavegenerated by the patient's heartbeat.

The pressure dome 7 of the transducer can include a diaphragm (notshown) which can respond to liquid pressure vibrations and engageelectrical strain means inside a transducer body 9 to convert hydraulicliquid pressure surges into electrical impulses. Such electricalimpulses are fed through a line 10 to an instrument 11 for reading thepressure fluctuations in a patient's cardiovascular system. Instrument11 can be an oscilloscope, an electronically activated stylus, etc. Ifdesired, the instrument 11 can have other monitoring functions, such asat 12 and 13, to monitor pulse rate, etc. in addition to blood pressurefluctuations at each heartbeat.

As explained above, the blood pressure monitoring for each heartbeatinvolves a liquid filled line between the patient and a diaphragm in thetransducer dome. Since there is no liquid flow across the diaphragm ofthe transducer, there is no continuous blood flow out of the patient.This is why in U.S. Pat. No. 3,581, 733 it is necessary to very slowlyforce a small volume of parenteral liquid, such as normal saline, intothe patient to prevent blood from backing up into the catheter andconnecting tube 2 where it could coagulate over an extended period oftime. Coagulated blood portions in the system can materially affect theaccuracy of a pressure monitoring because such coagulated blood forms arestriction in the hydraulic pressure system. This very slow infusion ofparenteral liquid (such as at 3 cc/hour) into the patient is from acontainer 15 supported on a pole structure 16. Preferably, container 15is of the collapsible bag type with a pressure cuff 17 that includes asqueeze bulb 18 and pressure gauge 19. The parenteral liquid flows fromcontainer 15 through a drip chamber 20 and a connecting tube 21 to avalve shown generally at 22 which is joined by flexible tube segment 23to the rigid T-connector 5. Flow through connecting tube 21 can becontrolled by conventional roller clamp 23.

The structure of the valve shown generally at 22 and the method ofassembling this valve is the subject matter of the present invention.Related co-pending co-owned applications filed on the same day as thepresent application are "Method of Flushing A Medical Liquid," filedApr. 24, 1979, Ser. No. 32,830 and issued as U.S. Pat. No. 4,267,833 onMay 19, 1981; "System For Flushing A Medical Liquid," filed Apr. 24,1979, Ser. No. 32,831, now U.S. Pat. No. 4,267,834, issued May 19, 1981;and "Protector Housing For Squeezable Valve" (Design), filed Apr. 24,1979, Ser. No. 32,971, now U.S. Pat. No. Des. 266,790, issued Nov. 2,1982.

In FIG. 2, the enlarged view of the valve illustrates a protectorhousing that includes a base 25 connected to ends 26 and 27, which inturn are connected to a top 28 that has a narrow central section 29.Within the protector housing is an elastically distortable squeeze tubeof rubber-like material, such as silicone. Preferably, this squeeze tubeis generally transparent, or at least translucent to aid in detectingany air bubbles in the valve.

As shown in FIG. 3, the top wall has a longitudinal bracing rib 32 whichextends through its longitudinal length to strengthen narrow portion 29of the top. Bottom wall 25 has a limit lug such as cradle 33, with aconcave surface, for preventing excess distortion of squeeze tube 30.Preferably, squeeze tube 30 has a generally triangular cross-sectionalshape.

In FIG. 3, the valve is shown in its normal continuous slow flow rateposition with the squeeze tube 30 sealingly engaging the periphery of arigid glass flow restrictor 40 that has a bore 41 with a diameter of0.001 to 0.004 inch. A diameter of 0.002 inch works very well and therestrictor can be made of glass tubing, such as is used for glassthermometers.

When it becomes necessary to fast flush the system of FIG. 1 with theparenteral liquid, the elastically distortable tube 30 is manuallypinched through side openings of the protector housing. This causes thetube 30 to temporarily distort and create a flushing passage 42 aroundrestrictor 40. When this is done, cradle 33 prevents undue flexure inthe valve which might dislocate the restrictor. Release of the squeezetube 30 causes it to immediately resume the FIG. 3 configuration and thepredetermined slow flow rate resumed.

Perhaps the valve structure can best be understood by referring to theenlarged sectional view in FIG. 5. Here the housing's end wall 26 isintegrally formed with a stationary hollow connector 45 which is joinedto flexible tube segment 23. End wall 27 of the protector housing isjoined to a tubular retainer 46 that has a bayonet type locking channel47. This bayonet type lock can also be seen in FIG. 2. Fitting withintubular retainer 46 is a longitudinally movable hollow connector 48which has a bayonet type lug 49 which engages slot 47 of retainer 46.Movable connector 49 has an internally tapered outer end and retainingears 50 for connecting with connecting tube 21 leading from theparenteral liquid source.

As liquid is delivered from the pressurized parenteral liquid source inthe system shown in FIG. 1, it flows to the left as shown by the flowarrows in FIG. 5. The liquid enters a hollow filter assembly 51 that isinside connector 48. After the liquid exits through sides of the filteras shown by the arrow, it travels to the flow restrictor 40 and thepressure forces the liquid through the restricted passage 41. Theelastic tube 30 tightly seals against the external periphery of glasstube 40 and prevents any other passage of liquid other than throughrestricted passage 41. To firmly hold ends of the tube 30 in place,compression shrink bands 52 and 53 can be used, if desired.

When it is desired to fast flush the system of FIG. 1, the elasticallydistortable tube 30 is laterally squeezed between thumb and forefingercausing an upper portion of tube 30 to lift off of the periphery ofglass tube 40 creating a flush passage. Thus, the liquid can flowthrough lateral passage 55 of connector 48, and go around restrictor 40and enter the passage of connector 45 through its lateral passage 56.

It is important that air bubbles be eliminated from the system as theycan interfere with the hydraulic pressure waves being transmitted fromthe patient to the transducer. For this reason, it is important that thehollow connectors 45 and 48 abuttingly engage ends of the restrictor 40so no undue pockets are formed which could trap air bubbles. It has alsobeen found that in cutting the glass flow restrictors 40, their lengthsometimes varies. To accept variable lengths of the restrictor 40, aswell as eliminating any undue pockets to trap air bubbles, a specialassembly method has been developed.

During assembly, the restrictor 40 is inserted into the squeeze tube andan end of tube 30 inserted on connector 45 which is fixedly joined tothe protector housing. The squeeze tube has a configuration as shown inFIG. 8 at the area of assembly to connector 45. Next the right endportion of squeeze tube 30 is angularly twisted as shown in FIG. 9 and atapered end of movable connector 48 inserted into a right end of tube30. Lug 49 is then inserted into an entrance 60 of the bayonet type slotof the housing's retainer 46. Preferably, retainer 46 has diametricallyopposed entrances 60 and 61 that are of different sizes which match withdifferent sized lugs on diametrically opposed sides of connector 48.Thus, the connector 48 will always be oriented in the proper position sothat its lateral port 55 is always at an upper part of the valve tocorrespond with the lateral port 56 of connector 45.

Once the connector 48 and tube 30 that has been temporarily twisted atone end with a torquing force have been assembled, lug 49 is tightenedin the bayonet slot 47. The squeeze tube 30 also has a certain degree ofelasticity that tends to untwist and tighten the connector 48. Thus, thebayonet type lock compressively urges the connectors 45 and 48 intocompressive engagement with ends of the glass restrictor 40. If glassrestrictor 40 varies slightly in length from one restrictor to the next,the bayonet structure can tolerate such variances. After the valve isassembled, the tube 30 resumes a shape generally shown at FIG. 10.

It has been found that the flushing valve of the present invention worksvery well when the flow restrictor is of glass, the squeeze tube is ofsilicone rubber, and the protective housing and hollow adapters are madeof a rigid thermoplastic material.

In the above description, a specific example has been used to illustratethe invention. However, it is understood by those skilled in the artthat certain modifications can be made to this example without departingfrom the spirit and scope of the invention.

We claim:
 1. A method of assembling a medical flushing valve comprisingthe steps of:(a) sealing a restrictor inside an elastically distortabletube so the restrictor and tube combine to form a flow passage with apredetermined flow rate leaving a portion of the distortable tubeextending beyond the ends of the restrictor; (b) securing one end of thedistortable tube to a first hollow connector fixed within a housing, andsecuring the other end of the distortable tube to a second hollowconnector which is movable with respect to the housing by twisting theelastically distortable tube with a torquing force and inserting themovable second hollow connector into the twisted end of the tube; and(c) compressingly urging the first and second hollow connectors intosealing engagement with the restrictor.
 2. A method as set forth inclaim 1, wherein the method includes orienting the movable connector toa predetermined rotational position when attaching to the tube so thatupon spiraling into sealing engagement with the restrictor a lateralport of the connector is at a particular rotational position.
 3. Amethod as set forth in claim 2, wherein the movable connector isoriented to its particular position by orienting latch means on abayonet type joint.